Just take extra precautions.. Wash your hands a lot and try to keep your distancr from your sister. Get a lot of sleep also to help ur immune system.. I know how you feel about getting sick Ive been struggiling my entire life w this phobia and I too didnt realize others felt the way I do. Which is comforting.. I hope ur feeling good! Try not to worry (easier said than done I know but had to say it)